Crankcase ventilation system



y 7, 1968 w. R. DRYSDALE 3,381,673

CRANKCASE VENTILATION SYSTEM Filed NOV. 22, 1965 INVENTOR. WILLIAM R.DRYSDALE BY w W ORNEYS United States Patent 3,381,673 CRANKCASEVENTILATION SYSTEM William Robert Drysdale, 355 Frederick Ava, Hayward,Calif. 94544 Filed Nov. 22, 1965, Ser. No. 509,035 6 Claims. (Cl.123-119) ABSTRACT OF THE DISCLOSURE An apparatus is described forconveying fumes from the crankcase of an engine into its fuel inductionsystem without allowing escape of such fumes to the atmosphere orpermitting them to adversely affect the air-fuel ratio of the inductionsystem. The apparatus includes two separate conduits which communicatethe engine crankcase with the fuel induction passage of the engine, oneof the conduits terminating at the induction passage at a position abovethe throttle valve and the other terminating below the throttle valve.An oil filler cap is provided with a Y- extension to facilitateconnection of the conduits to the crankcase, and a ring is adapted forpositioning in the induction passage between the air cleaner andcarburetor to provide a means for connecting one of the conduits to theinduction passage at a position above the throttle valve.

This invention relates to a system for removing fumes from the crankcaseof an internal combustion engine and preventing the same from harmingthe engine or contaminating the atmosphere. More particularly, theinvention relates to apparatus for conveying fumes from the crankcase ofan engine into its fuel induction system without allowing escape of suchfumes to the atmosphere, or permitting them to adversely affect the fuelcharge mixture in the induction system. The instant apparatusaccomplishes this while being easily installable on existing engines andwithout requiring the use of diaphragms, complicated valves or otherimpediments to the free flow of the fumes.

As is known, fumes tend to accumulate in the crankcase of an internalcombustion engine as a result of oil and moisture vaporization in thecrankcase, and flow of gases and carbon particles by the engine pistons.These fumes not only act deleteriously on the oil and engine parts, butnormally escape into the atmosphere to become one of the major causes ofatmospheric contamination. In an effort to obviate the results of thesefumes, various methods and apparatuses have been devised to convey thesame from the crankcase of an engine to its induction system so that thefumes maybe burned with the incoming fuel charge. Most commonarrangements involve the use of one or more conduits connecting thecrankcase to the induction system, and either the vacuum created in theinduction system or the pressure build-up within the crankcase isutilized to cause the desired flow of the fumes.

There are, in general, two types of ventilation systems now in use; theso-called closed system wherein the crankcase is sealed to theatmosphere, and the so-called open system wherein the crankcase isvented to the atmosphere. In systems of both of these types, it isusually necessary to provide valves, restrictions or other impedimentsin the conduits in order to control and limit the flow of fumes throughthe conduits so that such fumes will not unduly affect the air-fuelmixture of the fuel charge. However, fumes generally contain arelatively large proportion of particulate and liquid matters, such ascarbon, tars, and condensibles. The valves or restrictions act asimpediments to the free flow of fumes through the conduits and cause theparticulates and liquid matters to separate from the fumes. These tars,etc. quite often cause the valves to stick and the conduits to becomeclogged at the restrictions. Besides resulting in poor engineperformance, this sticking or clogging results in venting of the fumesinto the atmosphere in the open systems, and bursting of crankcase sealsand gaskets in the closed systems. At best, the provision of thesevalves or restrictions requires continual maintenance of the system toassure proper operation and to prevent harm from occurring to theengine.

Moreover, due to the criticality of the place of introducing the fumesinto the induction passage with most of these systems, specializedknowledge and engine modification is necessary for their installation.Presently, improper installations are often made and cause the systemsto malfunction to the detriment of the engine and its performance.

Accordingly, it is an object of the present invention to provide animproved crankcase ventilation system which will be effective under allengine operating conditions to convey all the fumes accumulating in acrankcase to the induction system and yet which does not require the useof valves or any other type of mechanical control.

Another object of the invention is to provide a crankcase ventilationsystem which introduces the fumes from the crankcase into the fuelinduction system without adversely affecting the carburetor or theair-fuel mixture of the fuel charge.

A further object of the invention is to provide a ventilation system ofthe character described which can be quickly and easily incorporated inexisting engines without requiring alteration of the engine orspecialized knowledge.

Still another object of the invention is to provide a ventilation systemof the character described which is free of all impediments such asvalves or impeding line restrictions to the free and even flow ofcrankcase fumes from the crankcase to the induction system.

One other object of the invention is to provide a crankcase ventilationsystem which can be utilized as either an open or closed system withequally as good results.

A still further object of the invention is to provide a chankcaseventilation system for an internal combustion engine which improves theengines performance and starting characteristics.

The invention possesses other objects and features of advantage, some ofwhich, with the foregoing, will be set forth in the followingdescription of the preferred form of the invention which is illustratedin the drawings accompanying and forming part of the specification. Itis to be understood, however, that variations in the showing made bysaid drawings and description may be adopted within the scope of theinvention as set forth in the claims.

Referring to such drawings:

FIGURE 1 is an end elevation of an internal combustion engine havingincorporated therewith the present invention in a preferred form, partsof such engine being shown broken away and in phantom;

FIGURE 2 is a perspective view of a ring of the ventilation systemespecially adapted to facilitate attachment of the ventilation systemwith the induction passage of an engine;

FIGURE 3 is a perspective view of a hollow fitting of the inventionwhich facilitates communication of the system with the crankcase of anengine through the oil filter pipe thereof;

FIGURE 4 is a cross-sectional view of the ring of FIGURE 2 depictingsuch ring incorporated into the induction system of an engine;

FIGURE 5 is a top plan view of the hollow fitting of 3 *IGURE 3 takenfrom a plane indicated by the lines 5-5 of FIGURE 1; and

FIGURE 6 is a cross'sectional view of the hollow fitting of FIGURE 3taken on planes indicated by the lines 66 of FIGURE 5.

In FIGURE 1 there is depicted generally schematically a conventionalinternal combustion engine 11 of the straight block type havingincorporated therewith a crankcase ventilation system 12 of the presentinvention. As shown the engine includes a valve chamber cover 13 and acrankcase 14, which crankcase has an oil inlet defined by oil fillerpipe 15. The valve chamber and crankcase are in communication with eachother through the block of the engine as is well known. Engine 11 alsoincludes a conventional induction system 16 defining an inductionpassagein which the fuel charge is mixed and fed to the cylinders of theengine. The induction passage of this system 16 is generally defined byan air cleaner 17, a carburetor 18, and an intake manifold 19. As isshown in phantom, the carburetor is provided with a conventional chokevalve 21 and throttle valve 22.

The crankcase ventilation system 12 includes a ring 23 adapted to bepositioned between the air cleaner and carburetor to define a portion ofthe induction passage. This ring 23 has a tubular extension 24 extendingoutwardly therefrom to which is suitably secured one end of a conduit 26such as by means of a ring clamp 25. The other end of conduit 26 issecured in a similar manner to a tubular extension 27 on a hollowfitting 28 which is adapted to fit within the oil filler pipe in placeof the usual cap therefor. A second tubular extension 29 extends fromhollow fitting 28 and has one end of another conduit 31 suitably securedthereto. The other end of this conduit 31 is adapted for securance intothe intake manifold 19 of the engine below the throttle valve 22. Inthis regard, it is to be appreciated that most intake manifolds areprovided with one or more fittings for communicating various apparatusessuch as a windshield wiper system or a conventional valve operatedventilation system to the intake. One of these fittings can beadvantageously utilized to communicably connect the conduit 31 to theintake to obviate the necessity of drilling or boring into the manifold.

From the above description and the drawing, it will be apparent that twosubstantially separate passageways are provided between the crankcaseand the induction passage, with one of these passageways terminatnig inthe induction passage just above or anterior of carburetor 1S and theother terminating in the induction passage below or posterior ofthrottle valve 22. With this arrangement, it has been found that byproperly sizing the passageways as will be discussed below, all of thefumes accumulating in the crankcase can be introduced into the inductionsystem without dirtying the carburetor, adversely affecting the air-fuelmixture, and without the necessity of providing valves or othermechanical controls or flow restricting impediments. In fact, it hasbeen ascertained that the presence of valves, restrictions or any othersubstantial impediment, projection or obstruction in the passagewaysinterfering with the free flow of fumes therethrough will cause theparticulates in the fumes to separate therefrom and clog thepassageways. This reduces the predetermined capacity of the passageways,thus preventing the adequate withdrawal of the fumes from the crankcaseand detrimentally upsetting the air-fuel ratio of the charge deliveredto the engine.

It has been further found that by properly sizing the capacity of thepassageways as will be discussed, the system can be utilized as eitheran open or closed system with equally good results. Moreover, the systemincreases the engines fuel utilization and improves the enginesperformance under certain operating conditions. Furthermore, because ofthe placement of the ring between the :air cleaner and carburetor, i.e.,directly above the carburetor, fumes entering the induction passage fromthe upper passageway will not get into or clog the air horns of ti ecarburetor. That is, as is known, the air horns of most carburetors arelocated at the top of the carburetor in the central portion of theinduction passage. Thus, the placement of the ring directly on top ofthe carburetor results in the upper conduit communicating with theinduction passage in approximately the same horizontal or lateral planeas the carburetor air horns. However, since the air horns are in themiddle of the passageway, and air is being drawn down through thecarburetor, the fumes from the conduit are drawn downward beforereaching the air horns. This is aided by the fact that a vortex actionis imparted to the fumes as they are drawn downward, and the heavyparticulate matter therein is caused by centrifugal force to remainadjacent the walls of the passageway away from the air horns.

All of the above is accomplished while, in addition, because of the ringand hollow fitting, the system can be easily and quickly installed onexisting engines. There is no necessity of drilling into the carburetor,or air cleaner to provide connection with the induction passage, nor isit necessary to drill into or provide special valved openings into thecrankcase. Because of the foregoing and the fact that the passagewaysare so sized, improper installations of the system are greatlyminimized.

The combined capacity of the two passageways should be such, withrespect to the fumes generated and the vacuum in the induction passage,that when the throttle valve 22 is open, all the accumulating fumes aredrawn from the crankcase and the pressure in the latter is maintainedapproximately at or below atmospheric pressure. However, the capacity ofthe passageway terminating below the throttle valve should be limitedwith respect to the fumes generated and the vacuum in the inductionpassage posterior of the throttle valve when it is closed so as tomaintain the leaning of the air-fuel mixture ratio due to theintroduction of the fumes within acceptable limits. In this regard, aleaning of the mixture by up to about 4 percent of its original air-fuelratio is considered by authorities to be acceptable. To satisfy thesecriteria, the minimum cross-sectional area of the paasageway terminatingwith the ring 23 should not be less than about .44 square inch (.75 inchin diameter), and the minimum cross-sectional area of the passagewayterminating below the throttle valve should be in the range betweenabout 4.4 10- square inches (.075 inch in diameter) and l.6 10- squareinches (.14 inch in diameter) depending on the engine size.

With engines having combustion chamber capacities up to cubic inches, ithas been found that for best results under all operating conditions, theminimum crosssectional area of the upper passageway, terminating withring 23 should be no less than .44 square inch (.75 inch in diameter)and the minimum cross-sectional area of the other lower passagewayshould be 5.8 10 square inches (.086 inch in diameter). For engineshaving combustion chamber capacities between 140 cubic inches and 250cubic inches, the minimum cross-sectional area of the upper passagewayis desirably no less than .78 square inch (one inch in diameter) and theminimum cross-sectional area of the lower passageway should be 8.8)(10square inches (.016 inch in diameter). For all engines having combustionchamber capacities greater than 250 cubic inches, excellent results areobtained if the minimum cross-sectional area of the upper passageway isat least .994 square inch (1.125 inches in diameter) and the lowerpassageway has a minimum cross-sectional area of 1.25 10- square inches(.126 inch in diameter). For all engines, it is desirable that each ofthe passageways have a generally constant cross-sectional areathroughout its length so that the free and even flow or fumestherethrough is not appreciably disturbed.

For a more detailed description of the ring 23 of the ventilationsystem, reference is made to FIGUR'ES 2 and 4. The ring is adapted forsecurance between the air cleaner 17 and carburetor '18 to provide aportion of the induction passage without requiring alteration of thecarburetor or air cleaner. More particularly, as will be apparent fromFIGURE 4, the air cleaner 17 is usually secured to the carburetor 18 bymeans of a scarf joint. For this reason, the upper and lower rim edgesof the ring 23 are provided with inwardly stepped chamfered surfaces 32and 33, respectively, adapted to mate with the corresponding chamferedsurfaces on the air cleaner 17 and carburetor '18. Wit-h thisconstruction, the joints between the ring and the air cleaner andcarburetor are smooth and continuous so that the surfaces defining theinduction passage are unbroken.

The engine induction systems of most automobiles are so designed thatwhen the hood of the automobile is down, very little clearance existsbetween the air cleaner and the hood. Thus, it is to be appreciated thatit is not possible to lengthen the induction passage to any great extentwithout having to modify the automobile hood or induction system. As aparticularly salient feature of the invention, the ring 23 is adaptedfor insertion into the induction passage without appreciably lengtheningit. More particularly, as can be seen from the drawing, the ring isrelatively thin. However, as noted above, the minimum cross-sectionalarea tubular extension 24 can have is .44 square inch. To provide thiscross-sectional area and yet permit the ring 23 to be relatively thin,it will be noted that the tubular extension 24 is constricted in therings axial direction and correspondingly lengthened in the ringstransverse direction .at the point at which it is joined to the ring.

As best depicted in FIGURES 3 land 6, hollow fitting 28 is provided witha stem 34 adapted to fit within, and friotionally engage, oil fillerpipe 15. The upper end of the fitting is closed by a cap 36 hingedlyconnected thereto. This cap provides access to the oil filler pipe, andhence the crankcase, for the introduction of oil.

A Y extension member 37 extends laterally from the hollow fitting 28 andis in communication with the interior thereof. The aforementionedtubular extensions 27 and 29 are formed by the arms of this Y member.With both of the passageways to the induction passage communicating withthe crankcase in this manner, it has been found that when the throttlevalve 22 is in its closed position and a high vacuum is consequentlyformed within intake manifold 19, all the crankcase fumes flow throughthe exten sion 29 and conduit 31 to the manifold, while fresh air, afterpassing through the air cleaner 17, is pulled int-o the crankcasethrough the conduit 26 and extension 27. This is particularly true inclosed systems and is advantageous therein in providing a means forintroducing clean fresh air into the crankcase without the necessity ofa oneway check valve or the like in the crankcase.

As mentioned before, the crankcase ventilation system of the inventionis equally applicable to both open and closed systems. When it is to beutilized as an open system, it is desirable that the fresh air inletinto the crankcase be provided by an opening within the hollow fitting28. More particularly, while not depicted, it is to be appreciated thata hole can be easily drilled or otherwise provided within the cap 36 forthis purpose. By providing an opening in the hollow fitting in thismanner, it is not necessary to modify the crankcase structure. I orderto assure sufiicient air flow into the crankcase with an open systemwithout adversely affecting the air fuel mixture of the inductionsystem, it is preferred that such an opening have a cross-sectional areaof approximately 5X10- square inches (.25 inch in diameter).

It is to be readily appreciated from the above that the crankcaseventilation system of the invention provides for the conveyance of allthe fumes generated in the crankcase to the induction system without thenecessity of providing any valves or other impediments in thepassageways. This is accomplished by the invention although it affords avery simple structure which can be easily installed on existing engines.To install the system, the hollow fitting 28 can be inserted in the oilfiller pipe in place of the conventional cap, and the ring 23 insertedbetween the air cleaner and carburetor. It is to be noted that with thisarrangement, in contrast to some others, it is not necessary to pass thefumes through the air cleaner or other filter to remove particulatestherefrom before the fumes are introduced to the induction passage abovethe carburetor. This increases the life of the air cleaner and,furthermore, does not hinder the removal of the air cleaner for changingof its filter or addition of oil.

What is claimed is:

1. A crankcase fume ventilation system for an internal combustion enginehaving a crankcase and members defining a fuel induction passage inwhich is provided a throttle valve, said system comprising a pair ofconduits communicably connecting the interior of said crankcase withsaid induction passage at points anterior and posterior of said throttlevalve, each of said conduits extending separately from at least adjacentsaid crankcase to said induction passage and each being devoid of allimpediments to the free and uniform fiow at all times of fumestherethrough from said crankcase to said induction passage whereby twosubstantially separate and clear passageways are defined between saidcrankcase and said induction passage with a first one of suchpassageways terminating anterior of the throttle valve in said inductionpassage and the second one terminating posterior of said throttle valve,the combined capacity of said two passageways with respect to the fumegenerated in the crankcase and the vacuum in said induction passagebeing such that When said throttle valve is open the pressure in saidcrankcase is maintained approximately at or below atmosphere pressure,and the capacity of the second passageway being limited with respect tothe fumes generated in the crankcase and the vacuum in said inductionpassage posterior of said throttle valve when said throttle valve isclosed to maintain the air-fuel ratio due to fumes entering theinduction passage from said second passageway within about 4 percentlean, the minimum cross-sectional area of said second passage being inthe range between about 4.4 x 10* square inches and 1.6 x 10' squareinches.

'2. The crankcase ventilation system of claim 1 adapted for use with aninternal combustion engine having a combustion chamber capacity of cubicinches or less and in which the minimum cross-sectional area of saidsecond passageway is about 5.8 x l0 square inches.

3. The crankcase ventilation system of claim 1 adapted for use with aninternal combustion engine having a combustion chamber capacity in therange between about 140 cubic inches and 250 cubic inches and in whichthe minimum cross-sectional area of said second passageway is about 8.8x 10- square inches.

4. The crankcase ventilation system of claim 1 adapted for use with aninternal combustion engine having a combustion chamber ca'pacity ofgreater than 250 cubic inches and in which the minimum cross-sectionalarea of said second passageway is about 1.25 x 10- square inches.

5. A crankcase fume ventilation system for an internal combustion enginehaving a crankcase with an oil filler inlet and an induction systemincluding an air cleaner and a carburetor defining a fuel inductionpassage in which is provided a throttle valve, said system comprising aring adapted for insertion between said air cleaner and carburetor andwhich has a central opening for defining a portion of the inductionpassage, said ring having an outwardly extending tubular extensiondefining a lateral passage in communication with said central opening; ahollow fitting mountable to said crankcase in communication with saidoil filler inlet of said crankcase, said hollow fitting having anoutwardly extending extension communicating with the interior thereofand a displaceable cap for the introduction of oil into said crankcase;a first conduit communica'bly connecting the extension on said fittingwith the extension on said ring to define a first passageway from saidcrankcase to said induction passage anterior of said throttle valve,conduit menas substantially separate from said first conduit andextending separately from at least adjacent said crankcase to saidinduction passage, said conduit means adapted for connection to saidinduction passage posterior of said throttle valve to define a secondpassageway from said crankcase substantially separate from said firstpassageway, both said first and second passageway being devoid of allimpediments to the free and uniform flow at all times of fumestherethrough from said crankcase to said induction passage, and bothpassageways having generally constant interior cross-sectional areasthroughout their length with the minimum cross-sectional area of saidfirst passageway being not less than .44 square inch and the minimumcross-sectional area of said second passageway being in the rangebetween about 4.4 x 10- square inches and 1.6 X 10* square inches.

8 6. The crankcase fume ventilation system of claim 5 wherein said ringis relatively thin and the tubular extension of said ring is constrictedat its joinder to said ring in the rings axial direction andcorrespondingly lengthened in the rings transverse direction.

References Cited UNITED STATES PATENTS 2,185,501 1/1949 Dress'ier 123i192,271,150 1/1942 Dressler 123119 2,462,634 2/1949 Griffiih 123-1192,818,052 12/1957 Trainer 123119 3,175,546 3/1965 Roper 123-1193,241,535 3/1966 Drysdale 123-119 AL LAWRENCE SMITH, Primary Examiner.

